As a known toner container of this type, there is a toner cartridge of cylinder rotation type equipped with a cylindrical container and a cap portion which holds an end of the cylindrical container in a rotatable manner (for example, the one described in PTL 1). FIG. 1 is an exploded cross-sectional view showing an end of a conventional toner cartridge of cylinder rotation type. In the drawing, a toner cartridge 500 includes a ring-shaped sealing member 501, a cap portion 510 serving as a lid, and a cylindrical container 530 in the form of a long cylinder. In the drawing, for the sake of convenience, the cap portion 510, the sealing member 501 and the cylindrical container 530 are separately shown, but in reality these are installed in a unified manner as shown in FIG. 2. Also, for the sake of convenience, regarding the cylindrical container 530, only an end thereof with respect to the cylinder axis direction is shown.
On the inner circumferential surface of a large-diameter cylindrical structure 511 of the cap portion 510, there is provided a hook portion 512 protruding toward the inner side of the cylinder. The cap opening side of this hook portion 512 is in a tapered form, whereas the opposite side thereof is in the form of a wall which rises substantially vertically from the circumferential surface. This surface which rises substantially vertically serves as a catching surface for catching the after-mentioned outer circumferential protrusion 533 on.
In the end of the cylindrical container 530, there is provided a container opening 531. On the outer circumferential surface of the end of the cylindrical container 530, there is provided an outer circumferential protrusion 533 extending around the whole circumference. Further, in the cylindrical container 530, there is provided a spiral groove 532 which is depressed (as if in an embossed portion) from the outer side toward the inner side of the container. This spiral groove 532 is in a spiral concave form as seen from the outside of the container but is in a spiral convex form as seen from the inside of the container.
Into the cap portion 510, the ring-shaped sealing member 501 and the end of the cylindrical container 530 are inserted as shown by the arrows in the drawing. At this time, the outer circumferential protrusion 533 of the cylindrical container 530 moves beyond the tapered protrusion of the hook portion 512 of the cap portion 510. Then the end of the cylindrical container 530 adheres to the sealing member 501. In this state, since the outer circumferential protrusion 533 of the cylindrical container 530 is caught by the catching surface of the hook portion 512, the cylindrical container 530 can be rotatably held by the cap portion 510 as shown in FIG. 2, without detaching from the cap portion 510.
In the main body of an image forming apparatus, when the cylindrical container 530 of the toner cartridge 500 is rotationally driven by a drive unit (not shown), a toner (not shown) accommodated in the cylindrical container 530 moves from the right-hand side toward the left-hand side in the drawing due to the spiral motion of the spiral groove 532. Then the toner moves into the large-diameter cylindrical structure 511 of the cap portion 510 through the container opening (denoted by 531 in FIG. 1) of the cylindrical container 530. Thereafter, the toner is discharged from a toner discharge port 515 of the cap portion 510 to the outside and then supplied into a developing device (not shown) that is a part of an image forming unit.
In the above structure, the ring-shaped sealing member 501 is affixed to a back surface of the cap portion 510 with double-sided tape so as not to detach.